It used to be when CCleaner said there was a new version and you followed the link you had the choice of picking the slim version from the other builds link.
Trouble is the other builds link no longer exists. http://www.piriform.com/ccleaner/download
I can find the light version by going to http://www.ccleaner.com/download/builds instead but why break the links for the lite version from the link built in the CCleaner.
Bill